Corrugated cardboard is a well-known inexpensive material for container construction. In many container applications, however, corrugated cardboard containers are not acceptable since they lack the required strength. Hence, more expensive materials, such as fiberboard and paperboard, have been employed. Containers of these materials are usually cylindrical drums.
In an effort to improve the strength characteristics of corrugated cardboard containers, multi-sided containers, that is, those including six or more sides, have been developed. A multi-sided container more closely approximates a cylindrical shape and, therefore, is structurally stronger than a square or rectangular corrugated cardboard container of the same capicity. In many cases the sides of such containers are sufficiently strong to replace hardboard or paperboard drums. However, difficulties have been encountered in closing the ends of the container. In other words, covers or other closure means used with multi-sided corrugated cardboard containers have either been so complicated as to be impractical or simply not strong enough.
The capability of corrugated cardboard containers to handle many of the situations which now call for fiberboard or paperboard drums not only offers the advantage of cost savings, but also solves a storage problem. Fiberboard or paperboard drums always take up the same amount of space even though they are empty and not in use. Since it is oftentimes necessary to keep a stock of containers on hand for periodic use in industrial situations, storage space must be set aside for these containers. Corrugated cardboard containers, on the other hand, may be stored in a flattened or knocked-down condition and assembled as called for. In other words, a user can keep a bundle of container blanks which may be formed into containers when needed. It should be apparent that a bundle of cardboard blanks take up less space than an equal number of drums. If the expanded use of corrugated cardboard is to be realized, however, an adequate cover must be available for closing the bottom of the container. The bottom cover is the most critical since it supports a large portion of the weight of the containers contents. In evaluating the adequacy of a cover, it should be kept in mind that the container assembly operation must not be difficult or excessively time-consuming in order to be practical.